Constant-load exercise decreases the serum concentration of myeloperoxidase in healthy smokers and smokers with COPD
There is an ongoing demand for easily accessible biomarkers related to pathophysiological processes in chronic obstructive pulmonary disease (COPD). Short-term intense exercise is known to increase the peripheral blood levels of cytokines. Therefore, we tested the potential and the repeatability of an exercise challenge to amplify seven serum biomarkers (interleukin 6 [IL6], C-reactive protein [CRP], myeloperoxidase [MPO], leukotriene B4, soluble intercellular adhesion molecule 1, soluble vascular cell adhesion molecule 1, and von Willebrand factor [VWF]) in smokers with and without COPD. Twenty-three smokers with moderate COPD (GOLD 2) and 23 sex- and age-matched healthy smokers underwent up to 30-minute submaximal, constant-load exercise (75% of maximum work load) on two occasions separated by 4 weeks (second challenge n=19/20). Serum samples were obtained before, 5 minutes after the start, at the end of exercise (maximum 30 minutes or until exhaustion), and after additional 20 minutes of rest. The median (interquartile range) exercise time until exhaustion in the two challenges was 10.0 (4.0) minutes and 10.0 (8.0) minutes in smokers with COPD and 22.0 (16.0) minutes and 26.5 (14.5) minutes in healthy smokers. The exercise challenge significantly increased the serum concentrations of IL6 and VWF, but decreased the concentrations of MPO. Healthy smokers showed a significantly greater increase (at the end of exercise compared to before exercise) in IL6 (P=0.01) and a larger decline (P=0.03) in MPO. The overall profile of the serum markers during the exercise challenge was shown to be repeatable in the second challenge. In summary, intense load exercise is capable of changing the concentration of inflammatory and endothelial function markers. Especially, the decline in the level of MPO, a marker closely related to cardiovascular risk, appears to be of clinical interest, as the exercise-induced decline might be related to the beneficial effects of physical activity in general.